Use 'guard against' when you want to prevent something unfavorable from occurring.

Negative Outcome

It implies taking early or cautionary steps to stop a bad thing before it starts.

Proactive Steps

The phrase suggests a continuous effort, not just a one-time action.

'Guard against' is used when taking action to address potential issues before they arise.

Focuses on measures to avoid future difficulties, often involves planning or foresight.

When we want to maintain something important, we 'guard against' its loss or deterioration.

The phrase can be used about protecting intangible things like traditions or languages.